Button

This demo depicts the way to add images and custom text to the date header bar by making use of the date header template
option.

DEMO

SOURCE

In this demo, the
dateHeaderTemplate option is used to customize the date header cells of day, week and workweek views. In month view, the date header
is not applicable and therefore the same customizations can be added beside the date text in the month cells by making
use of the
renderCell event.